Positive- and negative-working resist compositions with acid generating photoinitiator and polymer with acid labile groups pendant from polymer backbone

Abstract

Resists sensitive to UV, electron beam and X-ray radiation with positive or negative tone upon proper choice of a developer are formulated from a polymer having recurrent pendant groups such as tert-butyl ester or tert-butyl carbonates that undergo efficient acidolysis with concomitant changes in polarity (solubility) together with a photoinitiator which generates acid upon radiolysis. A sensitizer component that alters wavelength sensitivity may also be added.

We claim: 
     
       1. A resist composition comprising: a polymer and a photoinitiator which generates an acid upon exposure to radiation, the photoinitiator being present in from 1% to 100% by weight of said polymer, and the polymer having acid labile groups pendant from the polymer backbone, said groups being tertiary butyl esters of carboxylic acids or tertiary butyl carbonates of phenols, and   said resist composition being positive working when developed with alkaline developer or polar solvent to remove exposed areas of the composition and negative working when developed with a non-polar solvent to remove unexposed areas of the composition.   
     
     
       2. A resist composition as claimed in claim 1 which also contains a sensitizer that absorbs radiation and transfers energy to the photoinitiator. 
     
     
       3. A resist composition as described in claim 1 wherein the acid labile pendant groups are tert-butyl esters of carboxylic acids. 
     
     
       4. A resist composition as described in claim 1 wherein the acid labile pendant groups are tert-butylcarbonates of phenols. 
     
     
       5. A resist composition as claimed in claim 1 wherein the polymer is a poly (tert-butyloxycarbonyloxy-α-alkylstyrene) or a copolymer thereof. 
     
     
       6. A resist composition as claimed in claim 1 wherein the polymer is a poly (p-tert-butyloxycarbonyloxy-α-methylstyrene) or a copolymer thereof. 
     
     
       7. A resist composition as claimed in claim 1 wherein the polymer is a poly (tert-butyloxycarbonyloxystyrene) or copolymer thereof. 
     
     
       8. A resist composition as claimed in claim 1 wherein the polymer is a poly (p-tert-butyloxycarbonyloxy-styrene) or a copolymer thereof. 
     
     
       9. A resist composition as claimed in claim 1 wherein the polymer is a poly (tert-butyl vinylbenzoate) or a copolymer thereof. 
     
     
       10. A resist composition as claimed in claim 1 wherein the polymer is a poly (tert-butylmethacrylate) or a copolymer thereof. 
     
     
       11. A resist composition as claimed in claim 1 wherein the photoinitiator is an aryl diazonium salt. 
     
     
       12. A resist composition as claimed in claim 1 wherein the photoinitiator is an diaryliodonium salt. 
     
     
       13. A resist composition as claimed in claim 1 wherein the photoinitiator is triarylsulfonium salt. 
     
     
       14. A resist composition as claimed in claim 2 wherein the sensitizer is a dye. 
     
     
       15. A resist composition as claimed in claim 2 wherein the sensitizer is a polycyclic aromatic compound. 
     
     
       16. A resist composition as claimed in claim 2 wherein the sensitizer is pyrene. 
     
     
       17. A resist composition as claimed in claim 2 wherein the sensitizer is perylene.